Question

Discuss the levels,role, and importance of regulating gene expression within bacteria

Answer 1

Regulation of gene expression means to regulate genes to increase or decrease their activity in the production of gene products [protein and RNA]. It is achieved through a wide range of mechanisms used by cells.

For prokaryotes, most regulatory proteins are negative and therefore turn genes off. Here, the cells rely on proteins, small molecules binding, in which a ligand or small molecule signals the state of the cell and whether gene expression is needed.

In prokaryotes, like bacteria, transcription and translation occur simultaneously in the cytoplasm and regulation occurs at the transcriptional level.

Now, we all know that gene expression is essential because genes encode proteins and proteins dictate cell function. Each step in the flow of information from DNA to RNA to proteins provides the cell with a potential control-point for self-regulating its functions by adjusting the amount and type of protein it manufactures.

Bacterial genes are often found in operons. Each operon contains regulatory DNA sequences which act as binding sites for regulatory proteins that promote or inhibit transcription. The regulatory proteins often bind to small molecules which can make that protein active or inactive by changing its ability to bind to DNA.

Research has shown that transcriptional response in bacterial cells is controlled not only by the signaling metabolite cyclic AMP [cAMP]but also by the physiological state of the cell. This is so because bacterial cells continuously adjust gene expression in response to challenges from their environment. Several hundreds of transcription factors have been identified in E.coli. Of these, some might respond to stress and have only a few targets, others might coordinate the expression of hundreds of genes across a variety of cellular functions.

So, regulation of gene expression is important to help bacteria survive stressful environmental conditions like lack of nutrients and moisture, extremes of temperature etc. Perhaps this is how bacteria have been able to survive over centuries and withstand changes in earth's climatic conditions over eons. And perhaps this is also why bacteria are found almost at all places on the earth.